The overall hypothesis of this study is: the pulse profile of insulin for old persons (60-80yrs) will be different when compared to that of young persons(20-30 yrs). The more specific hypotheses are 1.) pulse profiles for young persons will have a larger pulse amplitude when compared to that of old persons; 2.)pulse profiles for young and old subjects will have similar pulse frequencies ; 3.)interpulse insulin secretion will be elevated in older persons and 4. a significant negative correlation will exist between insulin pulse amplitude and insulin sensitivity. It is clear that hormones stimulate greater biological responses when they reach the target tissue in a pulsatile manner (the physiological manner). We will document whether part of the cause for increased insulin resistance in older persons is partially due to an altered insulin pulse profile.